# How to create a timeline to accurately visualize a time series with some missing dates?

I'm trying to solve a medical mystery using data visualization. But I'm not very experienced in handling statistical data. My data does not have rows for every day of the year, only for dates which have a > 0 value. How can I avoid having to manually create the "empty" dates?

I have two years of data as a CSV file. The two columns are DATE and OCCURRENCES. Here are the first 10 rows:

2015-02-17,5
2015-02-18,7
2015-02-21,2
2015-02-23,2
2015-02-26,1
2015-02-27,1
2015-03-01,1
2015-03-02,1
2015-03-03,3
2015-03-05,2


Notice that there are no rows for dates which had 0 occurrences. Therefor, when I create a time-series chart in a spreadsheet program (Mac Numbers), the visualization does not show the empty days between occurrences.

I'm trying to visualize the data to see how and when the occurrences cluster together, and if there is a recurring pattern to the clusters. Before I go writing some Python script to add in the missing dates and populate them with '0', can someone tell me a smarter, better way of doing this? Thank you.